1. Field of the Invention
The present invention relates to an electrical socket assembly, and particularly to a socket assembly having built-in safety means preventing the insertion of a single pin into the contact opening connected to the live wire.
2. Brief Description of the Related Art
Sockets of this type are particularly intended to prevent insertion of conducting single pins into the live wire contact by, for example, playing children, without impeding insertion of a plug connected to an electric appliance into the socket.
The most widely used type of such safety sockets is one in which a rotatable disc having openings corresponding to the contact openings is affixed to the outer side of the cover of the socket, urged by a spring into a position in which the openings in said disc do not correspond to the contact openings, thereby preventing the insertion of anything into the contact openings. In order to insert the plug, it must be inserted into the openings of the disc and afterwards rotated against the force of said spring until the openings in the disc coincide with the contact openings, thereby connecting the appliance to the current source.
This relatively simple arrangement has two drawbacks. First, the cover disc may be also rotated by inserting a single pin into one opening and, after this opening is aligned with a contact opening, the single pin will enter the contact. If this contact is connected to the live wire, an accident may result. The second drawback is that the normal insertion of the plug is impeded. As a first step, the plug must be rotated until the openings in the cover disc are aligned with the contact openings.
There is known another type of safety socket, also intended to prevent insertion of a single pin into the contact openings. In this socket, both contact openings are covered by a sliding plate arranged on the inner side of the cover plate of the socket, slidable on the insertion of the plug in a direction normal to the line connecting the contact openings. The sliding plate is slidable only in the case when both contact pins of the plug are introduced simultaneously. Means are provided for locking the sliding plate in the covering position in case one tries to insert a single pin into one of the contact openings. A socket of this type is known, inter alia, from German Patent No. 22 10 513.